Fractionation



T. DE c. TIFFT ET AL Jan. 13,1931.

FRACTIONA TION Filed Jan. 23, 1928 I Z She etS-SheQt 1 INVENTORS' 771mm: 0LT. TIT/t William Mendz'us I zmmm/ Jan. 13, 1931. 1 T.DE C.TlFFT ETAL 7 05 FRACTIONATIONY I Filed Jan. 23, 1928 2 SheetsI-Sheet" 2 INVE N'fORS: 7710/22 1: d'C- 5 Wzllzam Men s K'TTORNEYS Patented Jan. 13, 1931 UNITED STATES. PATENT THOMAS DE COLON rrrr'r AND r0 smcmra ans-nuns column, or :anw you, n. 2., a coaromrron or mamamour-reunion I Application filed mu 19281 8ei'1a1 1Io. 248,794.

This invention relates to an improved tower for carrying out fractionating, refluxing or stripping operations or the like. The improved tower o the invention has several important advantages; in particular it combines advantages of open baflle towers and so-called bubble towers disadvantages of each.

The improved tower of the invention comprises a vertical shell, having a vapor inlet near the lower end and a vapor-outlet near the uppei end, a series of transverse partitions having openings adjacent alternate sides of the shell li 'uid weirs extending across and. upwardly from these partitions adapted to retain pools of liquid thereon on the side of the weirs inthe direction of vapor travel, and baflles adapted to function as inverted vapor weirs extending across and downwardly from these partltions spaced from the liquid weirs inthe direction of vapor travel. This construction provides alternation of high and low vapor velocities through the towerwith foaming or bubbling of liquid in regions of hifgh vapor velocity entrained liquid' followed by separation o from va or'm regions of low vapor'velocity before t e vapors enter the next region of high vapor velocity. This makes possible and application in the ing the invention as well accurate separation of higher and lower boiling components of liquid and vapor. At the same time .the tower is susceptible to immediate control and, further, adapts itself b to most variations normally encountered in operation. High capacity is also afforded.

This improved tower is of special distillation of complex mixtures such as petroleum oils. For example, this tower is well adapted for fractionation of gasoline from gasoline-containmg oil or vapor mixtures. The tower of the t invention, however, is useful generally for carrying out fractionatin'g, refluxing or stripping operations or'the like. a q The invention willbe further described in connection with the accompanying drawings whichillustrate one form of tower embodyas, diagrammatieally, operation of the improved tower of the mvention- In the accompanying drawings,

while eliminating" value Fig. 1 isa vertical section with parts broken away through a tower embodying the invention, Fig. 2 is a section on line 2-2 of Fig.

1, onan enlar ed'scale, Fig. 3 is a section on line 33 of ig. 2, Fig. 4 is an enlarged fragmentary detail, and Fig. 5 diagrammaticallZ illustrates the operation of the tower of 1ti e invention. Y

compmses a vertical shell 6 provided with a vapor inlet 7, a vapor outlet 8 and a li uid outlet 9.- A series of transverse partitlons -10 having openings 11 adjacent alternate eferring to Fig. 1, the tower illustrated 1 oFFIc-E mm mine, .or emeaeo, rumors, assrenons no each of the partitions 10, except the lowe :most. These bafiles 13 are spaced from the liquid weirs 12 on the next lower-partit1on in the direction of vapor travel to restrict vapor flow over the surface of the liquid pools retained by the liquid weirs to pathsofsmall cross-section immediately beneath the bafiles.

For use in refluxing or fractionating 0 erations, the tower ma be, cooled externally y exposure orpartia ex" osure to the atmosphere, .or internally ii a suitable coolin medium through a cooling coil arranged in the upper end of. the tower, as. illustrated at 1&1, or-by introduction into the upper end of the tower of a refluxing medium vaporizing substantially completely under the conditions of temperaure and pressure revailiri in the tower such as a portion 0 the con ensed, distillate product escaping from thetower as vapors, for example through a connection as 1l1us-. trated at 15. For use in stripping operations, heat may besupplied, for exam le, by direct introduction of. steam throug a perforated coil arranged in the lower end of the tower, as illustrated at 16, or by circulation of steam or other suitable heating y circulation of medium through a closed coil'arranged in the low'er endof the tower. It will be understoodv that fractionating or refluxing o erations and stripping operations may he carried out at the same time in-the same tower. Liquid may also be supplied to or withdrawn from intermediate points in the tower by connections similar to, that illus trated at 15. a

It is advantageous to provide means for conveying liquid from the partition nearest above the vapor inlet' to a lower point in the shell. In the tower illustrated, a lip 17 is provided on the lowermost'baffle 10 and a connection 18 is arranged to discharge liquid from behind this lip on this partition to a lower point in the shell. Connection 19 may be provided for taldng samples of this liquid. Particularly where a stripping operation is carried out in the tower, a few partitions with liquid weirs and baflies, arranged as just described, may be arranged in the tower below the vapor inlet, as shown at 20.

The partition, weir and battle construction illustrated, in Figs. 2 and 3 particularly, has several advantages. The bafiles 13 are made easily adjustable by providing sliding members 21 which can be clamped in any desired position by means of bolts 22 extending through slits in the sliding members. Access for adjusting these baffles is provided by an aligned series of openings having removable closures 23 through the series of partitions 10. I

In operation, vapors flowing upwardly through the tower pass inv through a series of. alternating regions of high vapor velocity and low vapor velocity. In the regions of high vapor velocity the vapors are compelled to pass in a restricted path over the surface of the pools of liquid so as to form bubbles or foam providing an enormous surface of contact between liquid and vapor. Entrained liquid separates from the vapors as next region of low vapor velocity, this separation being promoted by change in the direction of vapor travel. The liquid forming the several pools in the regions of high vapor velocity may be' condensate produced from the vapors'at ahigher point in (ill the tower .or may be anintroduced liquid or a mixture of these two. The liquid overflows from each pool to the next lower and from the lowest is discharged.- from the tower. The composition of the liquid dif fers, of course, through successive pools, the liquid containing decreasing proportions of higher boiling components and increasing proportions of lower boiling components in the direction of vapor travel through the tower. v

The pools of liquid maintained beneath the baflies in operation of the tower serve succession the mixture enters the,

in another capacity tower of invention a vantage.

Operations in which a uniform flow of vapors of uniform composition, exist are exceptional rather than the rule. These usual variations in vapor compositions and vapor volumes involve diiiiculty of control with most towers. These difliculties are particularly marked with the so-called bubble towers containing a large volume of liquid and consequently requiring a substantial amount of time to come to operating balance following external adjustments. In the improved tower of this invention, variations of vapor volume, of the total vapor volume or of the contained volume of some components, are usually accommodated by depression in the rther important adliquid pools beneath the bafiies,

through the tower or in particular regions of the tower, the tower thus adapting itself to such variations as are normally encountered. ,Due to the relatively small volume of contained liquid, moreover, operating balance follows external adjustments almost immediately with the improved tower of the invention.

This advantage makes the improved tower of the invention of special value and application where it is to handle vapors from some operation over which independent control must be maintained. For example, this tower is particularly useful for direct fractionation of gasoline from vapor mixtures from cracking operations. The ease of controlof the improved tower of 1giving the improved 7 or elevation of the liquid surface the invention further adds to its 'advan- V tages for such purposes.

Another advantage of the improved tower of the invention is the definite maintenance of intimate vapor and liquid contact and the persistent resistance'to channelling it provides in operation. With the so-called TI bubble towers, for example, horizontal vapor velocities beneath bubble caps may be high enough seal about the cap without adequate contact 'between vapor and liquid. In the improved tower of this invention, however, any such tendency is eliminated by the flow of liquid downwardly across the path of vapor travel beneath the vapor weirs.

The respective positioning of the liquid weirs and baflies varies for different operations. The, baflies may be set so that their .lower edges correspond approximately with to channel through the liquid I the static liquid level; behind the liquid weirs or they may be set below or above this point. Usually they are set somewhat above this point. The proportions and adjustments of the tower illustrated in Fig. '1 are those of a tower approximately five feet in. diameter and thirty feet high having four-' teen partitions between the vapor inlet and vapor outlet which has been used successfully in the fractionation of gasoline from pressure-cracking still naphthas.

We claim 1. An improved tower comprising a vertical'shell having a vapor inlet near the lower end and .a vapor outlet near the upper end, a series of transverse imperforate partitions arranged therein between the vapor inlet and vapor outlet, said partitions having openings adjacent alternate sides of the shell, liquid weirs extending across and upwardly from successive partitions, said liquid weirs being adapted to retain pools of liquid on the side of the weirs in the direction of vapor travel, and substantially verti-- Cal-bafiies extending across and downwardly from successive partitions, said bafiles being spaced fromsaid liquid weirs in the direc tion of vapor travel. 1

2. An improved tower comprising a vertical shell having a vapor inlet near the lower end and a vapor outlet 'near the upper end, a series of transverse partitions ar ranged therein between the vapor inlet and vapor outlet, said partitions having opene ings adjacent alternate sides of theshell, liquid weirs extending across and upwardly from said partitions, said liquidweirs-being adapted to retain pools of liquid on theside of the weirs inthe direction of vapor travel, adjustable baflies extending across and downwardly from said partitions, said baffles being spaced from saidliquid weirs in the direction of vapor travel and an aligned series of openings provided with removable closures through said series of transverse partitions. I

3. An improved tower comprising a vertical shell having a vapor inlet near the lower end and a vapor outlet near the upper end, a series of transverse partitions ar-. ranged therein between the vapor inlet and vapor outlet, said partitions having openings adjacent alternate sides of the shell, liquid weirs extending across and upwardly from said partitions, said liquid weirs being adapted to retain pools of liquid on the side of the weirs in the direction of vapor I travel, and bafiies extending across and downwardly from said partitions, said baflies being spaced from said liquid weirs in the direction of vapor travel and terminated above the upper extremities of the liquid weirs associated with the adjacent lower partitions.

4. An improved tower comprising a vertical shellhaving a vapor inlet near the lower' end and a vapor outlet near the upper end,

a series of transverse partitions arranged therein between the v. or inlet and vapor outlet, said partitions jacent alternate sides of the shell liquid weirs extending across and upwardly from said partitions, said liquid weirs beingaving openings ad- 5. An improved tower comprising a ver-' tical shell having a vaporinlet near the lower end and .a vapor outlet near'the upper end, a series of transverse imp'erforate partitions arranged therein between the vapor inlet and vapor outlet, said partitions having openings adjacent alternate sides of the shell, liquid weirs extending across and upwardly from said partitions, said liquid weirs being positioned a substantial distance from the edges of the partitions adjacent the openings thereto, and adapted .to retain pools of liquid on the side of the weirs in the direction of vapor travel, and vapor baffles'extending across and downwardly from said partitions, said bafiies being spaced from said liquid weirs in the direction of vapor travel.

In witness whereof, we have subscribed 0111'. names.

THOMAS DE COLON ITIPFFT. WILLIAM MENDIUS. 

